In various electronic systems employing microprocessors and integrated circuits it is desirable to eliminate the need to provide separate input pins for each analog input. Electronic systems such as the above-mentioned can be provided with an analog input from an internal resistor network or an external resistor network.
Thus, often times it is important that there be some means for monitoring that analog input to determine whether the electronic system is working from an internal or external mode. It is known that in many electronic systems, the internal mode may be a one voltage level, i.e., ten volts, but can then be divided down to a lower voltage to be used within the electronic system. It is also known that often times the signal from an external mode resistor network may have already been divided down externally and be provided to the input of the electronic system as a lower voltage, i.e., five volts.
Thus, accordingly what is needed is a circuitry that will be able to detect effectively and efficiently which mode the electronic system is in and provide the signal to indicate to the analog input of the electronic system that a certain mode has been detected. This circuitry should also be able to provide an indication via a digital output that the electronic system employed is in the external or internal mode.